Abnormality detection system of mobile robot

ABSTRACT

In an abnormality detection system of a mobile robot, it is configured such that it is self-diagnosed whether the quantity of state is an abnormal value, or whether at least one of the internal sensor, etc., is abnormal and when an abnormality is self-diagnosed, abnormality information is outputted, then the degree of abnormality is discriminated based on the outputted abnormality information and the robot is driven into a stable state in response to the discriminated degree of abnormality. With this, it becomes possible to effectively utilize the abnormality detection result. In addition, since the robot is driven into a stable state in response to the discriminated degree of abnormality, it becomes possible to render the driving appropriate.

TECHNICAL FIELD

This invention relates to an abnormality detection system of a mobilerobot.

BACKGROUND ART

As an abnormality detection system of a mobile robot such as a leggedmobile robot, there is known the technology taught by Japanese Laid-openPatent Application No. 2001-150374. This system diagnoses itself forabnormalities and informs the user (operator) of the result of thediagnosis by voice via an audio output device and a communicationsinterface, in a natural conversational manner.

However, in the aforesaid prior art, only the diagnosis result isoutputted and no measure whatsoever is taken with regard to the point ofdriving the robot 1 into a stable state when an abnormality occurs.

DISCLOSURE OF THE INVENTION

Therefore, it is an object of this invention to overcome thisinconvenience by providing an abnormality detection system of a mobilerobot that self-diagnoses whether or not an abnormality occurs and, whenan abnormality occurs, discriminates the degree of abnormality andaccordingly drives the robot into a stable state, thereby effectivelyutilizing the abnormality detection result.

In order to solve the aforesaid objects, this invention provides, asrecited in claim 1 mentioned below, a system for detecting abnormalityof a mobile robot having at least a drive motor, an internal sensor thatsenses a quantity of state of the internal of the robot and a controlunit constituted by an onboard microcomputer that operates the drivemotor based on the quantity of state obtained from an output of theinternal sensor to move, the control unit comprising: self-diagnosismeans for self-diagnosing whether the quantity of state is an abnormalvalue, or whether at least one of onboard equipments mounted on therobot including at least the drive motor and the internal sensor isabnormal; abnormality information outputting means for outputting, whenan abnormality is self-diagnosed by the self-diagnosis means,information of the abnormality; abnormality degree discriminating meansfor inputting the output of the abnormality information outputting meansand for discriminating degree of abnormality based on the abnormalityinformation; and stable state driving means for driving the robot into astable state in response to the discriminated degree of abnormality.Thus, since it is configured such that it is self-diagnosed whether thequantity of state is an abnormal value, or whether at least one of theinternal sensor, etc., is abnormal and when an abnormality isself-diagnosed, abnormality information is outputted, then the degree ofabnormality is discriminated based on the outputted abnormalityinformation and the robot is driven into a stable state in response tothe discriminated degree of abnormality, it becomes possible toeffectively utilize the abnormality detection result. In addition, sincethe robot is driven into a stable state in response to the discriminateddegree of abnormality, it becomes possible to render the drivingappropriate. It should be noted that, in this specification,“abnormality” means whole cases other than normal, which are non-normalconditions due to any events including deterioration, failure anddamages.

Further, this invention provides, as recited in claim 2 mentioned below,the system in which the stable state driving means drives the robot intoa stable state in response to the discriminated degree of abnormalitybased on a predetermined action plan chart. Thus, since it is configuredsuch that the robot is driven into a stable state in response to thediscriminated degree of abnormality based on a predetermined action planchart, in addition to the effects and advantages mentioned above, itbecomes possible to render driving into a stable state moreappropriately.

Further, this invention provides, as recited in claim 3 mentioned below,the system further including: abnormality degree storing means forstoring the discriminated degree of abnormality in an internal memoryprovided in the control unit and in an external memory provided outsidethe robot. Thus, since it is configured such that the discriminateddegree of abnormality is stored in an internal memory and in an externalmemory, in addition to the effects and advantages, it becomes possibleto improve the reliability of abnormality detection of the mobile robot.

Further, this invention provides, as recited in claim 4 mentioned below,the system in which the abnormality degree storing means stores theoutput of the abnormality degree discriminating means and a parameterindicative of the quantity of state of the robot, in an internal memoryprovided in the control unit and in an external memory provided outsidethe robot. Thus, since it is configured such that the degree ofabnormality and a parameter indicative of the quantity of state of therobot are stored in an internal memory and in an external memory, inaddition to the effects and advantages mentioned above, it becomespossible to ascertain accurately the course of events leading up to theabnormality, thereby enabling to further improve the reliability ofabnormality detection of the mobile robot. Further, it becomes possibleto drive the robot into a stable state by taking the quantity of stateinto account, thereby enabling to render driving into a stable statemore appropriately.

Further, this invention provides, as recited in claim 5 mentioned below,the system in which the control unit includes: dynamic model behaviorcorrecting means for inputting at least a desired manipulated variable,and based on a dynamic model which outputs a desired behavior of therobot, that is a plant, such that the desired manipulated variable issatisfied, correcting the behavior of the dynamic model, by additionallyinputting a correction amount of the desired manipulated variabledetermined in response to an error in the quantities of state of thedynamic model and the robot to at least the dynamic model; and controlmeans for controlling operation of the drive motor so as to follow thebehavior of the dynamic model; and the self-diagnosis meansself-diagnoses that the quantity of state is an abnormal value when theerror in the quantities of state of the dynamic model and the robot isnot within a predetermined value. Thus, when conducting the aforesaidcontrol, since it is configured such that the quantity of state isself-diagnosed to be an abnormal value when the error in the quantitiesof state of the dynamic model and the robot exceeds a predeterminedvalue, in addition to the effects and advantages mentioned above, itbecomes possible to detect the abnormality of the quantity of stateaccurately, thereby enabling to improve the reliability of abnormalitydetection of the mobile robot, and enabling to render the driving into astable state more appropriately.

Further, this invention provides, as recited in claim 6 mentioned below,the system in which the robot has a body and a plurality of leg linkageseach swingably connected to the body through a joint and each connectedwith a foot at its distal end through a joint, the internal sensorincludes an inclination sensor that generates an output indicative of aninclination of the body of the robot relative to a vertical axis, andthe self-diagnosis means self-diagnoses that the inclination sensor isabnormal when the output of the inclination sensor is not within apredetermined range. With this, in addition to the effects andadvantages mentioned above, it becomes possible to detect theabnormality of the inclination sensor as the internal sensor accurately,thereby enabling to improve the reliability of abnormality detection ofthe mobile robot, and enabling to render the driving into a stable statemore appropriately., thereby enabling to render the driving into astable state more appropriately.

Further, this invention provides, as recited in claim 7 mentioned below,the system in which the robot has a body and a plurality of leg linkageseach swingably connected to the body through a joint and each connectedwith a foot at its distal end through a joint; the internal sensorincludes an angle detector that generates an output indicative of atleast one of an angle, angular velocity and angular acceleration of thejoints, and the self-diagnosis means self-diagnoses that the angledetector is abnormal when the output of the angle detector is not withina predetermined range. With this, in addition to the effects andadvantages mentioned above, it becomes possible to detect theabnormality of the angle detector as the internal sensor accurately,thereby enabling to improve the reliability of abnormality detection ofthe mobile robot, and enabling to render the driving into a stable statemore appropriately.

Further, this invention provides, as recited in claim 8 mentioned below,the system in which the onboard equipments include an external sensorthat generates an output indicative of taken images. With this, inaddition to the effects and advantages mentioned above, when theexternal sensor is installed as the onboard equipments, it becomespossible to detect the abnormality of the sensor accurately, therebyenabling to improve the reliability of abnormality detection of themobile robot, and enabling to render the driving into a stable statemore appropriately.

Further, this invention provides, as recited in claim 9 mentioned below,the system in which the onboard equipments include a floor reactionforce detector that detects a floor reaction force acting on the robot,and the self-diagnosis means self-diagnoses that the floor reactionforce detector is abnormal when the output of the floor reaction forcedetector is not within a predetermined range. With this, in addition tothe effects and advantages mentioned above, when the floor reactionforce detector is installed as the onboard equipments, it becomespossible to detect the abnormality of the detector accurately, therebyenabling to improve the reliability of abnormality detection of themobile robot, and enabling to render the driving into a stable statemore appropriately.

Further, this invention provides, as recited in claim 10 mentionedbelow, the system in which the onboard equipments include sensors thatdetect a current supplied to the drive motor and a temperature of thedrive motor, and the self-diagnosis means self-diagnoses that the drivemotor is abnormal when at least one of the detected current andtemperature is not within a corresponding one of predetermined rangesset respectively with respect to the current and temperature. With this,in addition to the effects and advantages mentioned above, it becomespossible to detect the abnormality of the drive motor accurately,thereby enabling to improve the reliability of abnormality detection ofthe mobile robot, and enabling to render the driving into a stable statemore appropriately.

Further, this invention provides, as recited in claim 11 mentionedbelow, the system in which the onboard equipments include a battery thatsupplies a current to the control unit and the drive motor and a voltagesensor that generates an output indicative of a voltage of the battery,and the self-diagnosis means self-diagnoses that the battery is abnormalwhen the output of the voltage sensor is smaller than a predeterminedvalue. With this, in addition to the effects and advantages mentionedabove, it becomes possible to detect the abnormality of the batteryaccurately, thereby enabling to improve the reliability of abnormalitydetection of the mobile robot, and enabling to render the driving into astable state more appropriately. It should be noted here that the“abnormality of the battery” is based on the premise that the battery isregarded as normal if its output voltage is within a predeterminedrange.

Further, this invention provides, as recited in claim 12 mentionedbelow, the system in which the onboard equipments include a voicerecognition system that enables voice communication with an operator.With this, in addition to the effects and advantages mentioned above,when the voice recognition system is installed as the onboardequipments, it becomes possible to detect the abnormality of the voicerecognition system, thereby enabling to improve the reliability ofabnormality detection of the mobile robot, and enabling to render thedriving into a stable state more appropriately.

Further, this invention provides, as recited in claim 13 mentionedbelow, the system further including: an operator's operation controlunit provided outside the robot and comprising a microcomputer thatincludes the external memory; and communication means connecting thecontrol unit and the operator's operation control unit for establishingcommunication therebetween; and the self-diagnosis means self-diagnoseswhether the communication means is abnormal. With this, when thecommunication system is installed, it becomes possible to detect theabnormality thereof, thereby enabling to improve the reliability ofabnormality detection of the mobile robot, and enabling to render thedriving into a stable state more appropriately.

BRIEF EXPLANATION OF THE DRAWINGS

FIG. 1 is a front view of a mobile robot, specifically a legged mobilerobot, to which an abnormality detection system of a mobile robotaccording to an embodiment of this invention applies.

FIG. 2 is a side view of the robot shown in FIG. 1.

FIG. 3 is an explanatory diagram showing a skeletonized view of therobot of FIG. 1.

FIG. 4 is a block diagram showing the structural details of a controlunit and the like shown in FIG. 3.

FIG. 5 is a block diagram for explaining the operation of a generalstabilization control calculator shown in FIG. 4.

FIG. 6 is a flowchart of the operations of the abnormality detectionsystem of a mobile robot shown in FIG. 3.

FIG. 7 is an explanatory diagram showing an action plan chart used inthe flowchart of FIG. 6.

FIG. 8 is a flowchart showing a subroutine of the flowchart of FIG. 6.

FIG. 9 is a time chart for explaining the processing operations of theflowchart of FIG. 8.

FIG. 10 is a flowchart showing a subroutine of the flowchart of FIG. 6.

FIG. 11 is a flowchart showing a subroutine of the flowchart of FIG. 6.

FIG. 12 is time chart for explaining the processing operations of theflowcharts of FIGS. 10 and 11.

BEST MODE OF CARRYING OUT THE INVENTION

An abnormality detection system of a mobile robot according to anembodiment of this invention will be explained with reference to theattached drawings in the following.

FIG. 1 is a front view of a mobile robot, specifically a legged mobilerobot, to which an abnormality detection system of a mobile robotaccording to an embodiment of this invention applies, and FIG. 2 is aside view thereof. A biped humanoid robot is taken here as an example ofa legged mobile robot.

As shown in FIG. 1, the legged mobile robot (hereinafter called simply“robot”) 1 is equipped with a plurality of, more specifically two leglinkages 2 and a body (main unit) 3 above the leg linkages 2. A head 4is formed above the body 3 and two arm linkages 5 are connected one toeither side of the body 3. As shown in FIG. 2, a housing unit 6 ismounted on the back of the body 3 for accommodating therein, inter alia,a control unit (explained later). The robot 1 shown in FIGS. 1 and 2 isequipped with covers for protecting its internal structures.

FIG. 3 is an explanatory diagram showing a skeletonized view of therobot 1. The internal structures of the robot 1 will be explained withreference to this drawing, with primary focus on the joints. Asillustrated, the leg linkages 2 and arm linkages 5 on either the left orright of the robot 1 are equipped with six joints driven by 11 electricmotors (drive motors).

Specifically, the robot 1 is equipped at its hips (crotch) with electricmotors (drive motors) 10R, 10L (R and L indicating the right and leftsides; hereinafter the same) constituting joints for swinging orswiveling the leg linkages 2 around a vertical axis (the Z axis orvertical axis), electric motors 12R, 12L constituting joints for driving(swinging) the leg linkages 2 in the pitch (advance) direction (aroundthe Y axis), and 14R, 14L constituting joints for driving the leglinkages 2 in the roll (lateral) direction (around the X axis), isequipped at its knees with electric motors 16R, 16L constituting kneejoints for driving the lower portions of the leg linkages 2 in the pitchdirection (around the Y axis), and is equipped at its ankles withelectric motors 18R, 18L constituting foot (ankle) joints for drivingthe distal ends of the leg linkages 2 in the pitch direction (around theY axis) and electric motors 20R, 20L constituting foot (ankle) jointsfor driving them in the roll direction (around the X axis).

As set out in the foregoing, the joints are indicated in FIG. 3 by theaxes of rotation of the electric motors constituting (located at) thejoints (or the axes of rotation of transmitting elements (pulleys,etc.)) for transmitting the power of the electric motors. Feet 22R, 22Lare attached to the distal ends of the leg linkages 2.

In this manner, the electric motors 10R(L), 12R(L) and 14R(L) aredisposed at the crotch joints (hip joints) of the leg linkages 2 withtheir axes of rotation oriented orthogonally, and the electric motors18R(L) and 20R(L) are disposed at the foot joints (ankle joints) withtheir axes of rotation oriented orthogonally. The crotch joints and kneejoints are connected by thigh links 24R(L) and the knee joints and footjoints are connected by shank links 26R(L).

The leg linkages 2 are connected through the crotch joints to the body3, which is represented in FIG. 3 simply by a body link 28. The armlinkages 5 are connected to the body 3, as set out above.

The arm linkages 5 are configured similarly to the leg linkages 2.Specifically, the robot 1 is equipped at its shoulders with electricmotors 30R, 30L constituting joints for driving the arm linkages 5 inthe pitch direction and electric motors 32R, 32L constituting joints fordriving them in the roll direction, is equipped with electric motors34R, 34L constituting joints for swiveling the free ends of the armlinkages 5, is equipped at its elbows with electric motors 36R, 36Lconstituting joints for swiveling parts distal thereof, and is equippedat the distal ends of the arm linkages 5 with electric motors 38R, 38Lconstituting wrist joints for swiveling the distal ends. Hands (endeffectors) 40R, 40L are attached to the distal ends of the wrists.

In other words, the electric motors 30R(L), 32R(L) and 34R(L) aredisposed at the shoulder joints of the arm linkages 5 with their axes ofrotation oriented orthogonally. The shoulder joints and elbow joints areconnected by upper arm links 42R(L) and the elbow joints and wristjoints are connected by forearm links 44R(L).

The head 4 is connected to the body 3 through a neck joint 46 around avertical axis and a head nod mechanism 48 for rotating the head 4 aroundan axis perpendicular thereto. As shown in FIG. 3 (and FIG. 2), theinterior of the head 4 has mounted therein a vision sensor (externalsensor) 50 constituted as a CCD camera for taking and generating anoutput indicative of images, and a voice input/output device 52comprising a receiver and a microphone.

Owing to the foregoing configuration, the leg linkages 2 are eachprovided with 6 joints constituted of a total of 12 degrees of freedomfor the left and right legs, so that during locomotion the legs as awhole can be imparted with desired movements by driving the six jointsto appropriate angles to enable desired walking in three-dimensionalspace. Further, the arm linkages 5 are each provided with 6 jointsconstituted of a total of 10 degrees of freedom for the left and rightarms, so that desired tasks can be carried out by driving these 6 jointsto appropriate angles. In addition, the head 4 is provided with a jointand the head nod mechanism constituted of two 2 degrees of freedom, sothat the head 4 can be faced in a desired direction by driving these toappropriate angles.

Each of the electric motors 10R(L) and the like is provided with arotary encoder serving as an internal sensor (angle detector; designatedsolely by 56 in FIG. 4) that generates a signal corresponding to atleast one among the angle, angular velocity and angular acceleration ofthe associated joint produced by the rotation of the rotary shaft of theelectric motor.

A conventional six-axis force sensor (floor reaction force detector;external sensor) 58 is attached to each foot member 22R(L), generatessignals representing, of the external forces acting on the robot, thefloor reaction force components Fx, Fy and Fz of three directions andthe moment components Mx, My and Mz of three directions acting on therobot from the surface of contact.

In addition, an inclination sensor (posture sensor) 60 installed on thebody 3 as an internal sensor generates a signal representing at leastone of the inclination (tilt angle) relative to the vertical axis andthe angular velocity thereof, i.e., representing at least one quantityof state such as the inclination (posture) of the body 3 of the robot 1.The inclination sensor 60 is equipped with a main gyro and a sub-gyroinstalled separately of the main gyro in association therewith as abackup used when the main gyro malfunctions.

As shown in FIG. 2, the body 3 of the robot 1 accommodates a battery 64at its lower region and a main control unit constituted as amicrocomputer (hereinafter called the “main ECU 68”) at a housing unit 6provided on its back.

Distributed control units 70, 72, 74, 76, 78 and 80, also constituted asmicrocomputers (hereinafter called “distributed ECUs”), are installednear the aforesaid crotch joints, knee joints, foot joints, shoulderjoints, elbow joints and wrist joints.

In addition, distributed ECUs 82 and 84 are installed near and inassociation with the six-axis force sensors 58 and battery 64, while adistributed ECU 86 is installed at an appropriate location inassociation with the devices in the head 4. The distributed ECU 86receives the image signals generated by the vision sensor 50 and,together with the vision sensor 50, constitutes an image recognitionsystem for recognizing the environment or ambience of the robot 1through images.

The input and output of the voice input/output device 52 are alsoconnected to the distributed ECU 86. The distributed ECU 86 recognizesvoice instructions of the operator coming in via the receiver and sendsits voice output to the operator via the microphone, whereby, togetherwith the voice input/output device 52, it constitutes a voicerecognition system capable of voice communication.

The robot 1 is thus equipped with 16 distributed ECUs. The battery 64,which is capable of supplying direct current of 40[V], serves not onlyas an operating power source for the group of distributed ECUs but alsoas an operating power source for the electric motors 10R(L) and the likeand the main ECU 68 and the like. A voltage sensor 90 (shown in FIG. 4)installed at an appropriate point in the current supply circuit of thebattery 64 generates a signal representing the output voltage of thebattery 64.

As shown at the lower part of FIG. 3, an operator's operation controlunit (hereinafter called an “operator ECU”) 94 constituted as amicrocomputer is provided outside the robot 1 independently of the mainECU 68. A communication unit 96 is installed in the housing unit 6 forestablishing wireless communication between the main ECU 68 and theoperator ECU 94, thereby constituting a wireless system. The operatorECU 94 is equipped with an indicator (not shown).

FIG. 4 is a block diagram functionally illustrating the configuration ofthe main ECU 68, etc. The configuration of the main ECU 68 and the likewill be explained in greater detail with reference to this drawing. Themain ECU 68 is equipped with a controller 68 a, a macroscopic (orgeneral) stabilization control calculator 68 b and a shared memory 68 c,etc. The outputs of the rotary encoders 56, six-axis force sensors 58,inclination sensor 60, voltage sensor 90 and so forth are inputted tothe main ECU 68 and then stored in the shared memory 68 c.

The controller 68 a is equipped with a leg controller, arm controllerand head controller. The leg controller operates the individual electricmotors (drive motors) 10R(L) and the like through a group of motordrivers 100 and effect controlling for driving the leg linkages 2 andcausing locomotion, based on gait parameters generated beforehand, theoutputs of the inclination sensor 60 and the like representingquantities of state of the robot 1 stored in the shared memory 68 c andthe output of the external sensor comprising the six-axis force sensors58. As shown in FIGS. 2 and 3, a group of motor drivers 100 areaccommodated in the housing unit 6 as a circuit unit.

FIG. 5 is a block diagram for explaining the operations of themacroscopic stabilization control calculator 68 b that are discussedlater. As illustrated, the gait parameters include motion parameterscomprising the positions and postures (orientations) of the body 3 andfeet 22, and floor reaction force parameters defined by ZMP (Zero MomentPoint). “Position” is designated in an X, Y, Z coordinate system and“posture” is designated by angle relative to the X, Y and Z axes.“Inclination” is therefore one constituent of the parameter of theposture.

The gait is made up of the motion trajectory (locus) and the floorreaction force trajectory (locus) during one walking step (from thestart of the two-leg support period to the terminal or end of theone-leg support period). A series of walking amounts to a continuousseries of gaits in a single walking step.

Moreover, the arm controller of the controller 68 a controls the drivingof the arm linkages 5 in accordance with the nature of the task and thehead controller controls the driving of the head nod mechanism 48 inaccordance with the instructions of the image recognition system.

The macroscopic stabilization control calculator 68 b is equipped withdynamic model behavior correction means (actual inclination errorcontrol feedback rule) that, as shown in FIG. 5, based on the outputs ofthe inclination sensor 60 and the like representing quantities of stateof the robot 1 stored in the shared memory 68 c and the outputs of theexternal sensors constituted by the six-axis force sensors 58, inputs atleast a desired manipulated variable (a moment, more specifically, amodel manipulation moment Mmd1 about a desired ZMP) and using a dynamicmodel (robot perturbation dynamic model) which outputs a desiredbehavior of the robot (plant) 1 such that the desired manipulatedvariable is satisfied, corrects the behavior of the dynamic model, byadditionally inputting a correction amount of the desired manipulatedvariable (model manipulated moment Mmd1) determined in response to atleast the dynamic model and the quantity of state of the robot 1,specifically the error θerr of the inclination (inclination angle) ofthe body 3 relative to the vertical axis measured via the inclinationsensor 60, to at least the dynamic model, control means that controlsthe operation of the electric motors (drive motors) 10R(L) and the like,specifically joint displacement control means (displacement controller)that drives the electric motors 10R(L) and the like to control jointdisplacement to follow the behavior of dynamic model. Since the detailsof the macroscopic stabilization control calculator 68 b is described inJapanese Laid-Open Patent Application No. Hei 5(1993)-337849, filed bythe applicant, further explanation will be omitted.

The operator ECU 94 is equipped with a memory 94 a that functions as anexternal memory. The energizing circuits of the electric motors 10R(L)and the like are equipped with current sensors 102 that generate signalsrepresenting the energizing current supplied to the electric motors, andtemperature sensors 104, provided at appropriate locations on theelectric motors, generate signals representing the temperatures thereof.

Next, the abnormality detection (error checking) that is acharacteristic feature of this invention will be explained withreference to the flowchart of FIG. 6. The program indicated by theflowchart of FIG. 6 is executed once every 2.5 msec.

First, in S10, the macroscopic stabilization control calculator 68 b ofthe main ECU 68 conducts an error checking (abnormality detection(self-diagnosis)) by discriminating whether the quantities of state,i.e., the errors or deviations (inclination error) θerr of theinclination angle of the robot 1 relative to the dynamic model,specifically the error θerrx in the X-axis direction and the error θerryin the Y-axis direction, exceed predetermined angles (e.g., 20 degrees).

When the errors are respectively found to be within the predeterminedranges, the general stabilization control calculator 68 b discriminatesthat the quantities of state are normal, and when the errors in eitherthe X-axis direction or Y-axis direction is not within the predeterminedrange, it discriminates that the quantity of state is abnormal,whereafter, in S12, it outputs error information (abnormalityinformation), i.e., error information to the effect that the errorsθerrx or error θerry is too large, and then, in S14, it outputs theposture parameters at that time. The posture parameters include not onlythe aforesaid position/posture parameters of the body 3 and the like butalso the error θerr and the time since the robot 1 was activated.

Next, in S16, the macroscopic stabilization control calculator 68 bwrites the error information in the shared memory 68 c. As shown in FIG.4, the error information is also sent to a trouble detector 68 d.

Then, in S18, the trouble detector 68 d outputs an error occurrence log(record) affixed with an internal clock time stamp, i.e., it outputs theerror information (abnormality information) affixed with the time ofabnormality occurrence. The output of the trouble detector 68 d is sentto a trouble information integrated analyzer 68 e.

Then, in S20, the trouble information integrated analyzer 68 e notifiesan action planner 68 f of the rank (degree) of error, i.e., itdiscriminates the rank (degree) of the error (abnormality) based on theerror information to produce an output indicative of the discriminationresult and where it has been generated (in the case under discussion, inthe macroscopic stabilization control calculator 68 b). Then, in S22,the output is sent via the wireless system to the operator ECU 94 to bedisplayed on the indicator thereof so as to inform the operator that anerror (abnormality) has been detected.

Then, in S24, the action planner 68 f determines the next operation(action) in response to the degree of error and sends instructions tothe respective sections (the controller 68 a and the like), such thatcontrol is conducted in response to the discriminated degree to drivethe robot 1 into a stable state. Specifically, based on a predeterminedaction plan chart, it sends stable state transition control instructionssuch as for stopping locomotion in response to the discriminated degreesuch that the state of the robot 1 transits to a stable state. Then, inS26, the respective sections that receive the instructions (thecontroller 68 a and the like) perform the control in accordance with theaction plan chart.

FIG. 7 is an explanatory diagram showing the action plan chart. Asshown, the rank (degree) of the error occurred in the macroscopicstabilization control is determined to be FATAL, in this case thecontroller 68 a is instructed to stop the robot 1 immediately. The ranks(degrees) comprise the following:

FATAL . . . it means that the degree of error (abnormality) is of a highlevel. In this case, therefore, control is effected for immediatelystopping the robot.

WARNING . . . it means that the degree of error (abnormality) is of amedium level. In this case, therefore, the robot is not stoppedimmediately but control is continued for one walking step, i.e., untilcompletion of the walking step in progress, whereafter stable statetransition control is conducted to stop the robot.

SMALL . . . it means that the degree of error (abnormality) is of a lowlevel. In this case, therefore, only a measure such as informing theoperator is taken and no robot stopping control is performed.

The explanation of the flowchart of FIG. 6 will be continued. Next, inS28, upon ascertaining that operation of the robot 1 has terminated, inthis case upon confirming that the robot 1 stopped immediately, theaction planner 68 f generates walking or locomotion data required forerror analysis (specifically, the aforesaid motion parameters, floorreaction force parameters and so forth) and affixes a time stampthereto.

Next, in S30, the walking data and error log (record) are transferred tothe operator ECU 94 via the wireless system and saved (stored) in thememory (external memory) 94 a thereof. Then, in S32, the errorinformation (abnormality information) and the posture parameters aresaved (stored) in an internal flash memory (internal memory) 68 g.

The foregoing is the abnormality detection of the macroscopicstabilization control conducted by the main ECU 68. Next there will beexplained error checking (abnormality detection) of from the distributedECU 70 to the distributed ECU 84 (the ECU 86 for the head beingexcluded), which is conducted in S34.

FIG. 8 is a subroutine flowchart showing the error check of S34.

In S100, an error checking (abnormality detection) is conducted bydiscriminating, inter alia, whether the outputs in the 15 distributedECUs 70 to 84 are within predetermined ranges. Specifically,presence/absence of error is checked (self-diagnosed) by discriminatingwhether the outputs of the electric motors 10R(L) and the like, theinternal sensors, i.e., the rotary encoders 56 and inclination sensor60, and of the six-axis force sensors (external sensors) 58 are withinpredetermined ranges.

More specifically, with regard to the electric motors 10R(L) and thelike, discrimination is made as to whether the energizing currents andtemperatures detected from the outputs of the current sensors 102 andtemperature sensors 104 as set out above are within the respectivepredetermined ranges defined therefor, and when any of the detectedenergizing currents and temperatures is not within the correspondingrange, error is discriminated.

With regard to the rotary encoders 56 and inclination sensor 60,discrimination is made as to whether the values (inclination angle)detected from the outputs (output of the main gyro in the case of theinclination sensor 60) are within predetermined ranges, and when any ofthe outputs is not within the corresponding range, error isdiscriminated (self-diagnosed). Error detection with regard to theinclination sensor 60 is performed by the distributed ECU 70, forexample.

With regard to the distributed ECU 82 for the six-axis force sensors,discrimination is similarly made as to whether the outputs of thesix-axis force sensors 58 are within predetermined ranges, and when anyof the outputs is not within the corresponding ranges, error isdiscriminated (self-diagnosed).

With regard to the distributed ECU 84 for the battery, the outputvoltage of the battery 64 detected from the output of the voltage sensor90 is compared with a predetermined value and it is discriminated(self-diagnosed) that error has occurred in the battery 64 when theoutput voltage is smaller than the predetermined value.

When error is discriminated, the error information is transferred to themain ECU 68 in S102. FIG. 9 is a time chart of these processingoperations.

The error checking with regard to the distributed ECU 86 for the headwhich is conducted in S36, will be explained next.

FIG. 10 is a subroutine flowchart showing error checking of the wirelesssystem therein.

In S200, it is checked (self-diagnosed) whether a wireless system device(Ethernet (registered trademark) adapter or the like) is unusable orwhether the network processing result is a value outside a predeterminedrange (or whether the network processing result is detecting a valueoutside the predetermined range), and when the result is affirmative,error information is transferred to the main ECU 68 in S202.

FIG. 11 is a subroutine flowchart showing the error checking of theimage recognition and voice recognition systems therein.

In S300, it is checked (self-diagnosed) whether execution in response toa request is impossible or whether the result of execution is out of apredetermined range, and when the result is affirmative, errorinformation is transferred to the main ECU 68 in S302. FIG. 12 is a timechart of the processing of the wireless system and image/voicerecognition systems.

The explanation of the flowchart of FIG. 6 will be resumed. When errorinformation is transmitted from the distributed ECUs, the main ECU 68writes the error information to the shared memory 68 c in S16, outputsthe error occurrence log affixed with a time stamp in S18, and carriesout the processing operations set out above in S20 and onwards.

The processing operations of the action planner in S24 in the case wherethe error information is outputted from the distributed ECUs will beexplained with reference to FIG. 7. In such case, when abnormality ofthe electric motors 10R(L) and the like is discriminated, the degree(rank) of the abnormality is, as set out above, discriminated amongFATAL, WARNING and SMALL based on the abnormality information, and whenFATAL is discriminated, the robot 1 is immediately stopped byimplementing stable state transition control.

When WARNING is discriminated, control is continued until completion ofthe walking step of the robot 1 in progress, and when SMALL isdiscriminated, the only measure taken is to inform the operator, andcontrol of the robot 1 is continued.

The aforesaid three degrees (ranks) are established only for errordetection with regard to the distributed ECUs and only one degree isestablished for other errors. That is to say, when error isdiscriminated for the inclination sensor 60, FATAL is the onlydiscrimination made, in which case the action taken is to use the outputof the sub-gyro instead of the main gyro and to implement stable statetransition control for immediately stopping the robot 1.

When error is discriminated for the six-axis force sensor 58, FATAL isagain the only discrimination made, in which case the action taken is touse the sensor theoretical value and to implement stable statetransition control for immediately stopping the robot 1.

When error is discriminated for the power system (battery 64), WARNINGis the only discrimination made, in which case the control up to thatpoint is continued until completion of the walking of the robot 1 inprogress. The same also applies to the wireless system, voicerecognition system and image recognition system. In other words, controlis continued until completion of the operation because there is littlelikelihood of the robot 1 tipping over in such instances. It is noted,however, that is possible in such a case to effect control forimmediately stopping the robot 1 if there is no output during apredetermined time period of, say, 1 minute.

As explained in the foregoing, this embodiment is configured toself-diagnose whether the quantity of state of the robot 1 is anabnormal value, or whether at least one of the internal sensor such asthe inclination sensor 60 and the electric motor 10R(L), etc., isabnormal and when an abnormality is self-diagnosed, the abnormalityinformation is outputted, then the degree (rank) of abnormality isdiscriminated based on the outputted abnormality information and therobot 1 is driven into a stable state in response to the discriminateddegree of abnormality, it becomes possible to effectively utilize theabnormality detection result. In addition, since the robot is driveninto a stable state in response to the discriminated degree ofabnormality, it becomes possible to make the driving appropriate.

Further, since it is configured such that the robot is driven into astable state in response to the discriminated degree of abnormalitybased on a predetermined action plan chart, in addition to the effectsand advantages mentioned above, it becomes possible to render thedriving into a stable state more appropriately.

Further, since it is configured such that the degree (rank) ofabnormality and a parameter indicative of the quantity of state of therobot 1 (posture parameters) are stored in the internal memory 68 g andin the external memory 94, it becomes possible to ascertain accuratelythe course of events leading up to the abnormality, thereby enabling tofurther improve the reliability of abnormality detection of the mobilerobot. Further, it becomes possible to drive the robot into a stablestate by taking the quantity of state into account, thereby enabling thedriving into a stable state more appropriately.

In addition, since it is configured to self-diagnose that the quantityof state is an abnormal value when the error θerr of the quantity ofstate of the robot 1 relative to the dynamic model exceeds apredetermined value at the time of effecting the macroscopicstabilization control, it is possible to improve the reliability ofabnormality detection since the quantity of state abnormality can beaccurately detected, thereby enabling to render the driving into astable state more appropriately.

As stated above, this embodiment is configured to have a system fordetecting abnormality of a mobile robot having at least a drive motor(electric motor 10R(L), etc.), an internal sensor that senses a quantityof state of the internal of the robot and a control unit (main ECU 68)constituted by an onboard microcomputer that operates the drive motor(electric motor) based on the quantity of state obtained from an outputof the internal sensor to move, specifically a system for detectingabnormality of a mobile robot having at least a body 3 and a pluralityof (more specifically two) leg linkages 2 each swingably connected tothe body through a joint and each connected with a foot 22 at its distalend through a joint a drive motor (electric motor 10R(L), etc.), aninternal sensor that senses a quantity of state of the internal of therobot and a control unit (main ECU 68) constituted by an onboardmicrocomputer that operates (or drives) the drive motor (electric motor)based on the quantity of state obtained from an output of the internalsensor to move, the control unit comprising: self-diagnosis means (mainECU 68, distributed ECUs 70 to 86, S10, S34, S36, S100, S200, S300) forself-diagnosing whether the quantity of state is an abnormal value, orwhether at least one of onboard equipments mounted on the robotincluding at least the drive motor (electric motor) and the internalsensor is abnormal; abnormality information outputting means (main ECU68, S18) for outputting, when an abnormality is self-diagnosed by theself-diagnosis means, information of the abnormality; abnormality degreediscriminating means (main ECU 68, S20) for inputting the output of theabnormality information outputting means and for discriminating degreeof abnormality (the rank of error) based on the abnormality information;and stable state driving means (main ECU 68, S24) for driving the robotinto a stable state in response to the discriminated degree ofabnormality.

Further, it is configured such that, in the system, the stable statedriving means drives the robot into a stable state in response to thediscriminated degree of abnormality (the rank of error, morespecifically FATAL, WARNING and SMALL) based on a predetermined actionplan chart.

Further, it is configured such that, the system further including:abnormality degree storing means (main ECU 68, S30, S32) for storing thediscriminated degree of abnormality in an internal memory (internalflash memory 68 g) provided in the control unit and in an externalmemory 94 a provided outside the robot.

Further, it is configured such that, in the system, the abnormalitydegree storing means (main ECU 68, S30, S32) stores the output of theabnormality degree discriminating means and a parameter indicative ofthe quantity of state of the robot (posture parameters), in an internalmemory provided in the control unit and in an external memory providedoutside the robot.

Further, it is configured such that, in the system, the control unitincludes: dynamic model behavior correcting means (macroscopicstabilization control calculator 68 b) for inputting at least a desiredmanipulated variable and based on a dynamic model which outputs adesired behavior of the robot, that is a plant, such that the desiredmanipulated variable is satisfied, correcting the behavior of thedynamic model, by additionally inputting a correction amount of thedesired manipulated variable determined in response to an error in thequantities of state of the dynamic model and the robot to at least thedynamic model; and control means for controlling operation of the drivemotor (electric motor) so as to follow the behavior of the dynamicmodel, more specifically joint displacement control means (macroscopicstabilization control calculator 68 b) for driving the drive motor(electric motor) to conduct displacement control of the joints; and theself-diagnosis means (main ECU 68, S10) self-diagnoses that the quantityof state is an abnormal value when the error in the quantities of stateof the dynamic model and the robot, more specifically the error θerr ofthe inclination (angle) is not within a predetermined value.

Further, it is configured such that, in the system, the robot has a body3 and a plurality of leg linkages 2 each swingably connected to the bodythrough a joint and each connected with a foot at its distal end througha joint, the internal sensor includes an inclination sensor 69 thatgenerates an output indicative of an inclination of the body 3 of therobot relative to a vertical axis, and the self-diagnosis means(distributed ECU 70, S34, S100) self-diagnoses that the inclinationsensor is abnormal when the output of the inclination sensor is notwithin a predetermined range.

Further, it is configured such that, in the system, the robot has a body3 and a plurality of leg linkages 2 each swingably connected to the bodythrough a joint and each connected with a foot at its distal end througha joint; the internal sensor includes an angle detector (rotary encoder56) that generates an output indicative of at least one of an angle,angular velocity and angular acceleration of the joints, and theself-diagnosis means (distributed ECU 70, S34, S100) self-diagnoses thatthe angle detector is abnormal when the output of the angle detector isnot within a predetermined range.

Further, it is configured such that, in the system, the onboardequipments includes an external sensor (vision sensor 50) that generatesan output indicative of taken images.

Further, it is configured such that, in the system, the onboardequipments includes a floor reaction force detector (six-axis forcesensor 58) that detects a floor reaction force acting on the robot, andthe self-diagnosis means (distributed ECU 82, S34, S100) self-diagnosesthat the floor reaction force detector is abnormal when the output ofthe floor reaction force detector is not within a predetermined range.

Further, it is configured such that, in the system, the onboardequipments include sensors (current sensor 102, temperature sensor 104)that detect a current supplied to the drive motor (electric motor) and atemperature of the drive motor, and the self-diagnosis means(distributed ECUs 70 to 80, S34, S100) self-diagnoses that the drivemotor (electric motor) is abnormal when at least one of the detectedcurrent and temperature is not within a corresponding one ofpredetermined ranges set respectively with respect to the current andtemperature.

Further, it is configured such that, in the system, the onboardequipments includes a battery 64 that supplies a current to the controlunit and the drive motor (electric motor) and a voltage sensor 90 thatgenerates an output indicative of a voltage of the battery, and theself-diagnosis means (distributed ECU 84, S34, S100) self-diagnoses thatthe battery is abnormal when the output of the voltage sensor is smallerthan a predetermined value.

Further, it is configured such that, in the system, the onboardequipments include a voice recognition system (voice input/output device52, etc.) that enables voice communication with an operator.

Further, it is configured such that, the system further includes: anoperator's operation control unit (operator ECU 94) provided outside therobot and comprising a microcomputer that includes the external memory;and communication means (communication unit 96) connecting the controlunit and the operator's operation control unit for establishingcommunication therebetween; and the self-diagnosis means (distributedECU 86, S36, S200) self-diagnoses whether the communication means isabnormal.

Although it has been set out in the foregoing that, in abnormalitydetection for the drive motors (electric motors), internal sensors andthe like, abnormality is detected by comparing the outputs withpredetermined values, in other words with fixed values, it can insteadbe performed by providing a table or map. For instance, taking the powersystem (battery 64) as an example for the purpose of explanation, it ispossible to tabulate or map the expected battery voltage as a functionof the workload estimated from the time period and expected locomotionand define the predetermined value by retrieval from the table or map.

With regard to the six-axis force sensors 58, it is possible, forexample, to tabulate or map the expected time-course change in floorreaction force acting on the robot 1 as a function of the distance oftravel, time and the like of the expected locomotion and define thepredetermined value by retrieval from the table or map.

Although the explanation has been made taking a humanoid legged mobilerobot as an example of a mobile robot, this invention is not limitedthis but is similarly appropriate for application to a wheel or crawlertype mobile robot and also similarly appropriate for application to alegged mobile robot equipped with three or more leg linkages.

Although the explanation has been made taking an electric motor as anexample of a drive motor, this invention is not limited to this but ahydraulic motor, pneumatic motor or other such fluid pressure motor orthe like is also similarly appropriate.

INDUSTRIAL APPLICABILITY

According to this invention, in an abnormality detection system of amobile robot, since it is configured such that it is self-diagnosedwhether the quantity of state is an abnormal value, or whether at leastone of the internal sensor, etc., is abnormal and when an abnormality isself-diagnosed, abnormality information is outputted, then the degree ofabnormality is discriminated based on the outputted abnormalityinformation and the robot is driven into a stable state in response tothe discriminated degree of abnormality, it becomes possible toeffectively utilize the abnormality detection result. In addition, sincethe robot is driven into a stable state in response to the discriminateddegree of abnormality, it becomes possible to render the drivingappropriate. Therefore, this invention can be applied to an abnormalitydetection system of a mobile robot.

1. A system for detecting abnormality of a mobile robot having at leasta drive motor, an internal sensor that senses a quantity of state of theinternal of the robot and a control unit constituted by an onboardmicrocomputer that operates the drive motor based on the quantity ofstate obtained from an output of the internal sensor to move, thecontrol unit comprising: a. self-diagnosis means for self-diagnosingwhether the quantity of state is an abnormal value, or whether at leastone of onboard equipments mounted on the robot including at least thedrive motor and the internal sensor is abnormal; b. abnormalityinformation outputting means for outputting, when an abnormality isself-diagnosed by the self-diagnosis means, information of theabnormality; c. abnormality degree discriminating means for inputtingthe output of the abnormality information outputting means and fordiscriminating degree of abnormality in accordance with ranks defined inadvance including stopping of locomotion of the robot based on theabnormality information; and d. stable state controlling means forcontrolling the robot into a stable state in response to thediscriminated degree of abnormality based on a predetermined action planchart, wherein the stable state controlling means is configured toperform a plurality of actions and wherein the stable state controllingmeans, when controlling of the robot into the stable state, selects oneor more of said a plurality of actions depending on the discriminateddegree of abnormality.
 2. The system according to claim 1, furtherincluding: e. abnormality degree storing means for storing thediscriminated degree of abnormality in an internal memory provided inthe control unit and in an external memory provided outside the robot.3. The system according to claim 2, wherein the abnormality degreestoring means stores the output of the abnormality degree discriminatingmeans and a parameter indicative of the quantity of state of the robot,in an internal memory provided in the control unit and in an externalmemory provided outside the robot.
 4. The system according to claim 1,wherein the control unit includes: f. dynamic model behavior correctingmeans for inputting at least a desired manipulated variable, and basedon a dynamic model which outputs a desired behavior of the robot, thatis a plant, such that the desired manipulated variable is satisfied,correcting the behavior of the dynamic model, by additionally inputtinga correction amount of the desired manipulated variable determined inresponse to an error in the quantities of state of the dynamic model andthe robot to at least the dynamic model; and g. control means forcontrolling operation of the drive motor so as to follow the behavior ofthe dynamic model; and the self-diagnosis means self-diagnoses that thequantity of state is an abnormal value when the error in the quantitiesof state of the dynamic model and the robot is not within apredetermined value.
 5. The system according to claim 1, wherein therobot has a body and a plurality of leg linkages each swingablyconnected to the body through a joint and each connected with a foot atits distal end through a joint, the internal sensor includes aninclination sensor that generates an output indicative of an inclinationof the body of the robot relative to a vertical axis, and theself-diagnosis means self-diagnoses that the inclination sensor isabnormal when the output of the inclination sensor is not within apredetermined range.
 6. The system according to claim 1, wherein therobot has a body and a plurality of leg linkages each swingablyconnected to the body through a joint and each connected with a foot atits distal end through a joint; the internal sensor includes an angledetector that generates an output indicative of at least one of anangle, angular velocity and angular acceleration of the joints, and theself-diagnosis means self-diagnoses that the angle detector is abnormalwhen the output of the angle detector is not within a predeterminedrange.
 7. The system according to claim 1, wherein the onboardequipments include an external sensor that generates an outputindicative of taken images.
 8. The system according to claim 1, whereinthe onboard equipments include a floor reaction force detector thatdetects a floor reaction force acting on the robot, and theself-diagnosis means self-diagnoses that the floor reaction forcedetector is abnormal when the output of the floor reaction forcedetector is not within a predetermined range.
 9. The system according toclaim 1, wherein the onboard equipments include sensors that detect acurrent supplied to the drive motor and a temperature of the drivemotor, and the self-diagnosis means self-diagnoses that the drive motoris abnormal when at least one of the detected current and temperature isnot within a corresponding one of predetermined ranges set respectivelywith respect to the current and temperature.
 10. The system according toclaim 1, wherein the onboard equipments include a battery that suppliesa current to the control unit and the drive motor and a voltage sensorthat generates an output indicative of a voltage of the battery, and theself-diagnosis means self-diagnoses that the battery is abnormal whenthe output of the voltage sensor is smaller than a predetermined value.11. The system according to claim 1, wherein the onboard equipmentsinclude a voice recognition system that enables voice communication withan operator.
 12. The system according to claim 1, further including: h.an operator's operation control unit provided outside the robot andcomprising a microcomputer that includes the external memory; and i.communication means connecting the control unit and the operator'soperation control unit for establishing communication therebetween; andthe self-diagnosis means self-diagnoses whether the communication meansis abnormal.
 13. A system for detecting abnormality of a mobile robothaving at least a drive motor, an internal sensor that senses a quantityof state of the internal of the robot and a control unit constituted byan onboard microcomputer that operates the drive motor based on thequantity of state obtained from an output of the internal sensor tomove, the control unit comprising: a. self-diagnosis means forself-diagnosing whether the quantity of state is an abnormal value, orwhether at least one of onboard equipments mounted on the robotincluding at least the drive motor and the internal sensor is abnormal;b. abnormality information outputting means for outputting, when anabnormality is self-diagnosed by the self-diagnosis means, informationof the abnormality; c. abnormality degree discriminating means forinputting the output of the abnormality information outputting means andfor discriminating degree of abnormality based on the abnormalityinformation; d. stable state driving means for driving the robot into astable state in response to the discriminated degree of abnormality; e.dynamic model behavior correcting means for inputting at least a desiredmanipulated variable, and based on a dynamic model which outputs adesired behavior of the robot, that is a plant, such that the desiredmanipulated variable is satisfied, correcting the behavior of thedynamic model, by additionally inputting a correction amount of thedesired manipulated variable determined in response to an error in thequantities of state of the dynamic model and the robot to at least thedynamic model; and f. control means for controlling operation of thedrive motor so as to follow the behavior of the dynamic model, whereinthe self-diagnosis means self-diagnoses that the quantity of state is anabnormal value when the error in the quantities of state of the dynamicmodel and the robot is not within a predetermined value.